i am facing a wierd problem.. My MCU P89V51RD2BN resets during Execution... i am a college student and a beginner Here so i dont know the Advanced Programming methods i would also inform that..
i have a recursive function , a warning is issued by the compiler for the same. but....
earlier this was not a problem but since i have modified some of the Sub-Routines for 16Bit Data this Problem has come up, i need those functions to be 16 bit because of the limitation of the ALU i was earlier using 8bit and leaving most of the Task to Assumption which i cannot do so now..
i would also state that the Problem occurs in a fumction at a point when i call 2 functions in the same code, these themselves call around 5 sub-routines each but that wasnt a problem earlier (before i used the 16bit return type sub-routines).
now i found something in the manual stating reentrant Functions, but i really dont know how to use it
i used it like this
void Home_Screen_Instance() reentrant { ------------ } Do i need to use the keyword "reentrant" in the Function Decleration too? but that didnt help either but the compilers shows an error Home_Screen_Instance : redefinition. Target Not Created
this was the first of a kind problem that i encountered, my MCU is resetting itself for sure(i checked that with a dummy subroutine of blinking LED) and it is not because of the watchdog timer, i am sure about that too..
so whats the Problem here?
is the Stack overflowing??? or there is any other reason behind this? should i revert back to the 8bit versions of my subroutine (without any other choice)? is it because of the recursive nature of the function H0me_screen_instance?
Related Data:
The Program is Display intensive, i mean there are a lot of Strings to be displayed and they are stored beforehand in XDATA, message shown during sucessfull compilation, (still resets) Program Size: data 9.4 xdata 252 code 9514 creating hex-----blah blah blah---- 0 Error(s) 65 Warning(s)
what if i have to enter a 4 digit number, 9999 the maximum value i permit in this project as an user input can be contained by an unsigned int variable.. suggestions:
if (num_digit <= 4) { num *= 10; num + digit; num_digits++; }
or
if (num_digit <= 5 && Stack[0]<7) // im using a stack here,first element (MSB) is always at Stack[0] { num *= 10; num + digit; num_digits++; }
will this be fine?
also i suggest we do it at the end.. when the user has completed entering all the details, well it depends upon the number of characters being entered... yours look really good if the number of characters is large more than 5... i modified your code
unsigned int Temp2=0; while(Size>0) //Stack begins at 0, but Size is a natural Number { Temp2*=10; Temp2+=Stack[Stack_Top - Size]-'0'; //Stack_Top is at Size after the Execution --Size; }
now if the user is done with just one digit or two and i separately need to know that then Temp2%10 or Temp2%100 or like that..
what you are trying to overcomplicate has been done in very simple ways many, many times before.
Erik
sum = 0 for >max if !digit break sum *10 sum += digit
Note of course that the pseudocode for storing the digits in a integer do require an integer of proper size.
So an unsigned 8-bit variable have max range 255 and room for 2 digits. An unsigned 16-bit variable have max range 65,535 and room for 4 digits. An unsigned 32-bit variable have max range 4,294,967,295 and room for 9 digits.
In this specific case, a signed 8, 16 or 32-bit integer will have room for the same number of base-10 digits, allowing the function to return -1 for cancel or a value >= 0 for a properly entered number.
It takes many machine-code instructions to perform a 32-bit divide (for handling "backspace") but the C code will be very clean, saving coding and debugging time.